Overvoltage protection is critical to the long-term health of any cable. DC overvoltage testing (also known as withstand testing) is the most popular method of general condition and integrity assessment in the power, industrial and domestic markets. This method of testing is distinguished a number of key advantages:

Transient overvoltage on the supply, which is typically a very brief voltage spike, can be easily simulated and tested by DC withstand test equipment. DC withstand testing equipment is generally smaller and lighter than an equivalent AC test set. Because overvoltage tests are typically field based, being able to easily transport your tester is critical. Another significant advantage is that DC overvoltage testing has been a popular method for a long time, so there is plenty of historical data available from different technical bodies. Reference to these records allows operators to monitor condition quality through trend analysis. By regularly updating this data, insulation quality and integrity can be monitored indefinitely.

However, DC overvoltage testing is not always a perfect simulation of the stresses that power systems contend with on a day-to-day basis. For example, many power systems are subjected to frequencies of 50/60 hertz in their operational state, which are not always accurately represented. For conditions such as these, an AC test set is recommended.